Refrigeration – Processes – Circulating external gas
Reexamination Certificate
2000-09-19
2002-08-06
Doerrler, William (Department: 3744)
Refrigeration
Processes
Circulating external gas
C062S186000, C062S180000
Reexamination Certificate
active
06427455
ABSTRACT:
TECHNICAL FIELD
This invention relates to a cooling device to cool materials by circulating cold air with a cooling fan and also relates to a method of cooling with the device. Specifically, this invention relates to a cooling device used for freeze-storing foodstuff, a cooling device that cools materials during the conveyance, and a method of cooling with the cooling device.
BACKGROUND ART
In cooling devices such as freezers, a forced cold air circulating system is used for cooling. Air cooled by a cooling coil is forced to circulate by a cooling fan in a cooling chamber. Therefore, the cooling chamber has less inner temperature irregularity and cooling time is decreased.
For example, in a conventional freezer, a partition divides the inner space into a cooling coil part having a cooling coil such as a fin-tube type and a cooling fan, and a freezing chamber for freeze-storing foodstuff. The cooling coil is connected with a compressor, a condenser, or the like. A refrigerant circulates in these elements and evaporates in the cooling coil.
To circulate cold air between the freezing chamber and the cooling coil part, a ventilation port and a suction port are provided. The ventilation port discharges cold air from the cooling coil into the freezing chamber while the suction port sucks cold air of the freezing chamber into the cooling coil.
Air cooled by the cooling coil is discharged into the freezing chamber by the cooling fan via the ventilation port. Foodstuffs inside the freezing chamber are cooled with the cold air flowing in the freezing chamber. The air heated by heat exchange with the foodstuffs is sucked by the suction port into the cooling coil part, cooled again by the cooling coil, and ventilated into the freezing chamber.
An example of conventional cooling devices to cool food in the conveyance by means of this cooling method is mentioned more specifically in the following. Cooling devices that cool food during the conveyance include spiral freezers, tunnel freezers, or the like. A spiral freezer cools food on a belt moving spirally by a rotating drum in a thermal insulating box. A tunnel freezer cools food on a belt moving horizontally in a thermal insulating box.
FIG. 11
shows a cross section in a horizontal direction of a conventional spiral freezer. A thermal insulating box
21
is formed by filling a thermal insulator
23
between metal plates
22
. A food inlet
24
and a food outlet
25
are formed in the thermal insulating box
21
. A belt-driving plate
28
is attached spirally to the outer periphery of a rotating drum
27
that rotates around a shaft
26
(FIG.
12
). A belt
29
is mounted on the belt-driving plate
28
.
A food delivery belt
30
is provided to the food outlet
25
. The rotating drum
27
integrated with the belt-driving plate
28
is placed in a tubular drum case
31
. A cooling unit case
32
is connected to the drum case
31
.
Inside the cooling unit case
32
, a cooling coil
33
, cooling fans
34
, an air course
35
for discharging cold air, and an air course
36
for sucking cold air are formed. Typically, the cooling coil
33
is a fin-tube.
FIG. 12
shows a cross-section in the vertical direction of the conventional spiral freezer shown in
FIG. 11. A
rotating drum
27
is disposed inside the drum case
31
with an attachment column (not shown) in order to rotate around the shaft
26
.
FIG. 13
shows a cross section taken along a line I—I of FIG.
11
. In
FIG. 13
, the cross-section along the line I—I is overlapped with a cross section comprising the food inlet
24
part and the food outlet
25
part in order to clarify the condition of the food conveyance. The cooling coil
33
is connected with a compressor, a condenser, etc (not shown). A refrigerant circulates in these elements, and evaporates in the cooling coil
33
.
A process for cooling food is explained below by referring mainly to FIG.
11
. First, a foodstuff is delivered into the thermal insulating box
21
from the food inlet
24
. The foodstuff is mounted on the belt
29
and moves in a direction indicated by an arrow ‘a’. The belt
29
is shaped like a ring as. a whole and mounted by being combined with the belt-driving plate
28
.
As shown in
FIG. 13
, when the food conveying drum
27
rotates, the belt
29
moves upward along the surface of the spirally-shaped belt-driving plate
28
due to an extruding force created by the rotation of the belt-driving plate
28
integrated with the food conveying drum
27
, and also by a drawing force of the belt
29
provided by a separate driving power source. As the belt
29
is shaped like a ring, it circulates on the belt-driving plate
28
. A foodstuff
38
, which reaches the top step of the belt-driving plate
28
due to the moving belt
29
, continues to move in a direction indicated by an arrow ‘b’ to the food outlet
25
, and delivered with a food delivery belt
30
out of the thermal insulating box
21
. In this process of the upward move of the foodstuff
38
at the food conveying drum
27
, the foodstuff
38
is cooled.
As shown in
FIG. 11
, cold air from the cooling coil
33
is discharged by the cooling fans
34
in a direction indicated by arrows labeled ‘c’. The cold air then passes through an air course
35
for discharging cold air and discharged into the drum case
31
. Cold air in the drum case
31
moves up the respective steps of the belt-driving plate
28
along the inner wall of the drum case
31
so that the foodstuff on the belt
29
is cooled. The foodstuff
38
is cooled continuously while it moves from the bottom step to the top step of the belt-driving plate
28
, and thus cooling is completed by the time the food reaches the top step.
In the drum case
31
, the cold air is heated by heat exchange with the foodstuff and returns to the cooling coil
33
through a cold air suction part
36
. The returning air is cooled again by the cooling coil
33
and discharged by means of the cooling fans
34
in the direction indicated by the arrows labeled ‘c’.
To ventilate cold air uniformly from the bottom to the top steps of the belt-driving plate
28
, the height of the cooling coil
33
is adjusted to be substantially equal to the height from the bottom to the top step of the belt-driving plate
28
, and a plurality of cooling fans
34
are arranged to substantially cover the entire surface of the front of the cooling coil
33
as shown in FIG.
12
.
FIG. 14
shows a vertical cross-section in the longitudinal direction of a conventional tunnel freezer. A thermal insulating box
39
is formed by filling a thermal insulator
40
between metal plates
41
. In the upper portion of the thermal insulating box
39
, a plurality of cooling coils
42
are aligned in the longitudinal direction.
At the rear of respective cooling coils, cooling fans
43
are arranged. A continuous belt
44
for conveying foodstuffs circulates by moving horizontally in the thermal insulating box
39
. Additionally, a food inlet
45
and a food outlet
46
are formed in the thermal insulating box
39
.
First, when foodstuff is mounted on the belt
44
at the front of the food inlet
45
, the foodstuff passes the food inlet
45
together with the moving belt
44
and moves in the thermal insulating box
39
in a direction indicated by an arrow ‘d’. Cold air discharged from the cooling coil
42
in a direction indicated by an arrow ‘e’ by the cooling fans
43
moves in the directions indicated by arrows ‘f’, ‘d’, and ‘g’, and returns to the rear of the cooling fans
43
. The returning air passes through the respective cooling coils
42
sequentially to be discharged again in the ‘e’ direction. By means of such a circulation of cold air, foodstuffs on the belt
44
are cooled while being moved in the ‘d’ direction.
The above explanation is about an example of conventional cooling devices. In such cooling devices, the temperature of air returning to a cooling coil increases due to heat exchange with foodstuff, and the air contains vapor generated from the foodstuffs. When the returning air is cooled again by the cooling coil, moisture
Doerrler William
Light Shoki Kabushiki Kaisha
Rosenthal & Osha L.L.P.
Shulman Mark
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